feat: enrich 209 skills with MITRE ATLAS, D3FEND, and NIST AI RMF frontmatter

Added structured security framework mappings to SKILL.md frontmatter across all applicable skills:
- atlas_techniques: MITRE ATLAS v5.5 AML.TXXXX IDs (81 skills, AI-targeted attack techniques)
- d3fend_techniques: MITRE D3FEND v1.3 defensive technique labels (139 skills, mapped from ATT&CK IDs)
- nist_ai_rmf: NIST AI RMF 1.0 subcategory IDs (85 skills, AI risk management functions)

Also updates ATTACK_COVERAGE.md with coverage statistics for all three frameworks.

skills/detecting-qr-code-phishing-with-email-security/SKILL.md

@@ -1,12 +1,27 @@
 ---
 name: detecting-qr-code-phishing-with-email-security
-description: Detect and prevent QR code phishing (quishing) attacks that bypass traditional email security by embedding malicious URLs in QR code images within emails.
+description: Detect and prevent QR code phishing (quishing) attacks that bypass traditional email security by embedding malicious
+  URLs in QR code images within emails.
 domain: cybersecurity
 subdomain: phishing-defense
-tags: [quishing, qr-code, phishing, email-security, image-analysis, ocr, mobile-security]
-version: "1.0"
+tags:
+- quishing
+- qr-code
+- phishing
+- email-security
+- image-analysis
+- ocr
+- mobile-security
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+atlas_techniques:
+- AML.T0052
+- AML.T0024
+- AML.T0035
+nist_ai_rmf:
+- MEASURE-2.8
+- MAP-5.1
 ---
 # Detecting QR Code Phishing with Email Security